"wanton and furious cycling" only applies if an injury is suffered. And by injury, the law means serious injury or death as a direct result of the cyclists actions. Your friend should have challenged the accusation. "National" speed limits only apply to "motor" vehicles. Not to non-electric pedal cycles.
Local bylaws mean that there is an 8mph speed limit on Hampstead Heath and a 20mph speed limit in Richmond Park.
We are all weary of the tiresome personal claim TV adverts by Slater & Gordon but they summarise cycling law and speed as well as anyone
https://www.slatergordon.co.uk/media-centre/blog/2015/06/can-cyclists-break-the-speed-limit-or-does-the-law-only-apply-to-motorists/
Incidentally, if I was doing 8mph I would probably fall off
Local bylaws mean that there is an 8mph speed limit on Hampstead Heath and a 20mph speed limit in Richmond Park.
We are all weary of the tiresome personal claim TV adverts by Slater & Gordon but they summarise cycling law and speed as well as anyone
https://www.slatergordon.co.uk/media-centre/blog/2015/06/can-cyclists-break-the-speed-limit-or-does-the-law-only-apply-to-motorists/
Incidentally, if I was doing 8mph I would probably fall off